Process of manufacturing paper from straw.



U NTTED STATES PATENT OFFICE.

LI IHVIG K. litlllM, OF NElV YORK, N. Y., ASSIGNOR TO \VILLIAM S.MACCLYHONT, Oh SAME PLACE.

PROCESS OF MANUFACTURING PAPER FROM STRAW.

SPECIFICATION formingpart of Letters Patent No. 659,784, dated October16, 1900.

Application filed March 2, 1900. Serial No. 7,666. (No specimens- To milIU/hO/f'b it may con/corn..-

lie it known that I, Luowio K. Boinn, a citizen of the United States ofAmerica, and a resident of New York, in the county of New York and Stateof New York, have invented certain new and useful lln provements inProcesses of Manufacturing Paper from Straw, of which the following is aspecification.

My invention relates to improvements in the process of manufacturingpaper, and particularly to improvements in the manufacture of paper-pulpfrom straw; and it is the object of this invention to prepare paperpulpfrom straw of such quality that the same may be worked up into variousgrades of printing and particularly writing paper, while heretoforegenerally packing and wrapping paperthat is, very cheap paper of aninferior grade-has been made from straw.

As is well known, straw contains Iiber-bundles of special length, andthe incrustations thereon are of such chemical nature as to be removableby chemical agents, exposing thereby the real fiber, and after suchchemical treatment a fiber is obtained which is and remains soft andflexible and may be easily bleached. Straw-pulp therefore is wellapplicable in paper-making, and, in fact, has been used formanufacturing packing and wrapping paper and partly for admixing withother pulps in the manufacture of finer grades of paper. The reason whystraw as a substitute material for linen rags in paper-making has notbeen more extensively used is that straw was not obtainable in suchquantities as, for instance, wood for wood-pulp, especially in Europe,while at present great quantities of straw are obtainable in the UnitedStates which are wasted, burned up on the fields, and practically of novalue. Straw therefore represents a very cheap and easilyobtainable rawmaterial for preparing pulp for paper-making; and it is the object ofthis invention to provide a process by means of which straw is moreutilized for making all kinds of paper. 111 attaining this purpose Isubstantially proceed as follows: The straw first is freed from weeds,if such are present. Then it is put into any suitable tank. It may becut into short pieces of from one to two inch lengths; but this is notnecessary.

The stalks maybe worked up in their full length. First the straw istreated in a di lulcd solution of acetic acid of from three to five percent. strength. The tank in which the straw is first. treated isprovided with an arrangement for introducing steam, which issues eitherdirectly into the solution or passes through a worm. (are should betaken that the temperature in the tank can be raised to from 100" to 130centigradc. After the straw has been boiled in this solution from fourto six hours then same is drawn off, representing then a dark-browndirty liquid. The straw now is washed out in the same tank. The purposeof this treatment in a dilute solution of acetic. acid is a doubleonefirst, the straw is washed thereby, so that a clean material isobtained, and at the same time all water-soluble substances areextracted, and, second, the acetic acid tends to soften the straw and atthe same time binds those organic substances which are bases or of abasic character, thus removing them therefrom. After the straw has thusbeen prepared it is treated in the same tank with a solution of causticsoda. The strength of this solution varies with the kind and grade ofpaper to be made out of the pulp and increases with the better qualityof the paper to be made. For common paper ten per cent. of caustic sodais sufficient, provided the straw has been first treated as abovedescribed, and for the finer grades the quantity of caustic sodaincreases up to twenty-five per cent. This chemical treatment iscontinued for about seven or eight hours,while the temperature is raisedby steam to from 100'to 130 centigrade, when all the silicic acid andthe gummy and fatty substances contained in the straw will be taken out.Now the steam is turned 0E, and the dirty caustic lye is drawn 0E, andthe remaining softened straw, representing pure fiber, is washed out inthe same tank, first with hot water, then with cold water, and finallywith a very weak solution-say of one or two per cent.--of acetic acid.So far the straw has retained the full length of its stalks, whichsimplifies the processes of washing out and prevents practically anyloss of material. Now the straw is removed into the hollander, where itis washed and torn up for several hours, until the softened straw hasbeen reduced to a pulpy mass and so-called hall'- stuff is produced. Nowthis pulp is treated with blcaehing-powder solution in the usual manner;butaftcr the bleaching solution has been acting on the pulp for abouttwo hours then some acetic acid is added for the purpose of facilitatingthe elimination of the hypochlorous acid in the bleaching solution. Theacetic acid is added gradually in very small quantities and in a verydilute condition. After the process of bleaching has been finished, thepulp is washed out in the usual manner or treated with an antichlor andthen Washed out, when it is ready for the heating or breaking machine,the fiber as treated so far having not yet been sufficicntlydisintegrated for fine qualities of paper. In the breaking-machine thepulp is treated for from four to six hours until the properdisintegration of the fiber is efiected. For fine qualities of paper theknots or joints of the straw are separated from the pulp in suitablemachinery. After the pulp leaves the breaking-machine it is againbleached, if same should be necessary or if very fine paper shall bemade therefrom, and now the pulp is ready for loading, sizing, coloring,

llaving thus described my invention, I claim as new and desire to secureby Letters l.atcnt 1.. The process of making paper-pulp from straw,consisting in first treating the straw in a boiling solution of dilutedacetic acid, then washing out thestraw, then treating it in a boilingsolution of caustic soda, removing the caustic lye, by washing withwater, then washing it with a very dilute solution of acetic acid, thendisintegrating the straw for the purpose of obtaining the pulp and thenbleaching same as specified.

2. The process of making paper-pulp from straw, consisting in treatingthe straw in a boiling solution of dilute acetic acid, then washing itout, then treating it in a boiling solution of caustic soda, removingthe caustic lye, then reducing the straw in order to obtain so-calledhalf-stuff, bleaching it, heating it for the purpose of producing finepulp, then bleaching it again, and then working the pulp up into paper,as specified.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

LUDXVIG K. BUHM.

WVitnesses:

EVELYN GREEN, LOUISE WIEDMANN.

